Adaptive optics near-infrared observations of magnetars

Abstract

<Context>. We report on near-infrared (IR) observations of the three anomalous X-ray pulsars XTE J1810-197, 1RXS J1708-4009, 1E 1841-045 and the soft gamma-ray repeater SGR 1900+14, taken with the ESO-VLT, the Gemini, and the CFHT telescopes. <Aims>. This work is aimed at identifying and/or confirming the IR counterparts of these magnetars, as well as at measuring their possible IR variability. <Methods>. In order to perform photometry of objects as faint as Ks~20, we have used data taken with the largest telescopes, equipped with the most advanced IR detectors and in most of the cases with Adaptive Optics devices. The latter are critical to achieve the sharp spatial accuracy required to pinpoint faint objects in crowded fields. <Results>. We confirm with high confidence the identification of the IR counterpart to XTE J1810-197, and its IR variability. For 1E 1841-045 and SGR 1900+14 we propose two candidate IR counterparts based on the detection of IR variability. For 1RXS J1708-4009 we show that none of the potential counterparts within the source X-ray error circle can be yet convincingly associated with this AXP. <Conclusions>. The IR variability of the AXP XTE J1810-197 does not follow the same monotonic decrease of its post-outburst X-ray emission. Instead, the IR variability appears more similar to the one observed in radio band, although simultaneous IR and radio observations are crucial to draw any conclusion in this respect. For 1E 1841-045 and SGR 1900+14, follow-up observations are needed to confirm our proposed candidates with higher confidence.

9 pages, 10 figures; accepted by A&A (high resolution images at http://staff.science.uva.nl/~nrea/NIR_AXP_testa2007.pdf)

References in corpus (13)

• Transient pulsed radio emission from a magnetar
• Corona of Magnetars
• A Debris Disk Around An Isolated Young Neutron Star
• 1E 1547.0-5408: a radio-emitting magnetar with a rotation period of 2 seconds
• Discovery of luminous pulsed hard X-ray emission from anomalous X-ray pulsars 1RXS J1708-4009, 4U 0142+61 and 1E 2259+586 by INTEGRAL and RXTE
• Magnetars as persistent hard X-ray sources: INTEGRAL discovery of a hard tail in SGR 1900+14
• The Compact X-ray Source 1E 1547.0-5408 and the Radio Shell G327.24-0.13: A New Proposed Association between a Candidate Magnetar and a Candidate Supernova Remnant
• The Anatomy of a Magnetar: XMM Monitoring of the Transient Anomalous X-ray Pulsar XTE J1810-197
• Search for radio pulsations in four Anomalous X-ray Pulsars and discovery of two new pulsars
• Spectral modelling of the high energy emission of the magnetar 4U 0142+614
• Swift and Chandra confirm the intensity-hardness correlation of the AXP 1RXS J170849.0-400910
• Intensity-hardness correlation and deep infrared observation of the anomalous X-ray pulsar 1RXS J170849-400910
• The infrared counterpart to the magnetar 1RXS J170849.0-400910

Cited by in corpus (9)

• The strongest cosmic magnets: Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars
• Magnetars: Properties, Origin and Evolution
• From outburst to quiescence: the decay of the transient Anomalous X-ray Pulsar XTE J1810-197
• Where are the magnetar binary companions? Candidates from a comparison with binary population synthesis predictions
• Submillimeter pulsations from the magnetar XTE J1810-197
• New candidates for magnetar counterparts from a deep search with the Hubble Space Telescope
• VLT/NACO near-infrared observations of the transient radio magnetar 1E 1547.0-5408
• The infrared counterpart and proper motion of magnetar SGR0501+4516
• VLT observations of the magnetar CXO J164710.2-455216 and the detection of a candidate infrared counterpart